Mars Time Zone

 Scientists say time runs faster on Mars, Messier as compare to earth and moon

The National Institute of Standards and Technology (NIST) fulfills a vital role in national security: employing the sort of people who would, if they got bored, take over the world. It takes a specific kind of person to run the persnickety gravitational calculations of exactly how fast clocks tick on Mars relative to the Earth. Thanks to NIST, two of these people have recently shared their calculations, instead of building a lair under a volcano to perform evil experiments. They found that Mars time runs faster than Earth time, and considerably messier. Thanks to Einstein’s relativity, time flows differently on Mars than on Earth. NIST scientists have now nailed down the difference, showing that Mars clocks tick slightly faster, and fluctuate over the Martian year. These microsecond shifts could play a big role in future Mars navigation, communications and even a solar-system-wide internet. It’s a small time gap with big consequences for space exploration. Mars time runs faster and cracking that cosmic time gap could help humanity spread across the solar system. Gravitational lensing, or light bending around massive objects, is another example of general relativity at play.  

In strong gravitational fields, time flows more slowly. Albert Einstein first described this effect, known as time dilation, in his 1915 theory of general relativity. Scientists working in precision timekeeping must account not only for the Earth’s gravity, but also that of the Sun and Moon. They have become very good at that. The evidence is on your phone: the accuracy of GPS is thanks to minute adjustments to clock rates in different locations around the Earth. Future spacefarers will need to know the exact time on Mars relative to the Earth. Any kind of precision location system, such as GPS, depends on clock rate conversions. The new study by NIST, models the gravitational field on Mars at different points throughout its orbit to predict what that clock rate should be. They double-check their results using in-situ gravitational observations from Mars. On Earth, finding the exact time is effortless. Our planet relies on a sophisticated global system which combines atomic clocks, GPS satellites and ultra-fast communication networks to keep everything in sync. The precision does not extend naturally beyond Earth. Albert Einstein showed that time does not move at the same pace everywhere in the universe. The rate at which a clock ticks depends on gravity, meaning clocks run slightly slower in stronger gravity and faster in weaker gravity. Even coordinating time across Earth is complex. Extending that coordination across the solar system is far more challenging. For future explorers hoping to live and work on Mars, one fundamental question must be answered first: What time is it on Mars?

The Juno spacecraft contributed Martian gravity measurements as it flew past the red planet. Modelling Martian time is a lot more complicated than it is for the Earth. Not only is it harder to actually take measurements which would allow scientists to check their math, but the math itself also involves more factors. Mars’ lower mass means gravity is a lot weaker on its surface than on Earth. Even without external effects, Martian time flows faster than Earth time. But the Mars time to Earth time conversion depends on a lot more than Mars’s gravitational field. The biggest complication for time on Mars is the eccentricity of its orbit. Eccentricity describes how elongated and oval-shaped an orbit is, as opposed to circular. Since Mars’ orbit is considerably more eccentric than Earth’s, its distance from the Sun varies much more. Mars’s lower mass, only 10% of the Earth’s, also makes it easier for other bodies in the Solar System to push it around. While the motion of Mars doesn’t affect the Earth’s gravity much, the motion of Earth matters a lot to Mars. The ever-changing locations of the Sun and the Earth push and pull on the surface gravity of Mars and, consequently, its clock rate. Physicists at the National Institute of Standards and Technology (NIST) have now produced a precise answer. Their calculations show that, on average, clocks on Mars tick 477 microseconds (millionths of a second) faster per day than clocks on Earth. This difference is not constant. Because of Mars' stretched orbit and gravitational influences from other bodies, the time difference can vary by as much as 226 microseconds/day throughout the Martian year.

The NIST scientists outlined a framework for highly precise timekeeping on the Moon. Understanding how time passes on Mars is essential for future missions, said NIST physicist Bijunath Patla. As NASA prepares for more advanced Mars exploration, accurate timing will be critical for navigation, communication and coordination across planetary distances. "The time is just right for the Moon and Mars," Patla said. "This is the closest we have been to realizing the science fiction vision of expanding across the solar system." A difference of 477 millionths of a second may seem insignificant. It is roughly one thousandth of the time it takes to blink. Yet such tiny differences matter greatly in modern technology. For example, 5G communication systems require timing accuracy within a tenth of a microsecond. Today, messages sent between Earth and Mars take anywhere from four to 24 minutes to arrive, and sometimes even longer. Patla compared the situation to communication before the telegraph, when handwritten letters crossed oceans by ship and replies took weeks or months to return. Developing a reliable framework for timekeeping between planets could eventually allow for synchronized communication networks across the solar system. "The time is just right for the Moon and Mars. This is the closest we have been to realizing the science fiction vision of expanding across the solar system." Bijunath Patla, NIST physicist says. "If you get synchronization, it will be almost like real-time communication without any loss of information. You don't have to wait to see what happens," Patla said.

To make the calculations possible, NIST researchers selected a specific reference point on the Martian surface, comparable to sea level at Earth's equator. Using data gathered from years of Mars missions, Patla and fellow NIST physicist Neil Ashby estimated surface gravity on Mars, which is about five times weaker than Earth's. Gravity from Mars alone was not enough to explain the full picture. The solar system is a dynamic environment filled with massive objects which constantly pull on one another. The Sun contains more than 99% of the solar system's total mass, and its gravitational influence dominates planetary motion. Mars' location in the solar system, its distance from the Sun, its neighbors like Earth, the Moon, Jupiter and Saturn, forces it into a more elongated and eccentric orbit. By contrast, Earth and the Moon follow relatively stable paths. As a result, time on the Moon consistently runs 56 microseconds faster/day than time on Earth. "But for Mars, that's not the case. Its distance from the Sun and its eccentric orbit make the variations in time larger. A three-body problem is extremely complicated. Now we're dealing with four: the Sun, Earth, the Moon and Mars," Patla explained. "The heavy lifting was more challenging than I initially thought." After accounting for Martian surface gravity, orbital motion, and the gravitational effects of the Sun, Earth and Moon, Patla and Ashby arrived at their final calculation.

Although Mars time changes over the course of a Martian year, the authors found an average difference of 421.5 microseconds (millionths of a second, or μs)/day between Mars and the Earth. It doesn’t sound like much, but think of it this way: For every day that passes on Earth, Mars falls behind our clocks by 421.5 μs. If we don’t model and compensate for the difference, that’s enough to render 5G wireless, for instance, totally useless. By predicting this discrepancy, the authors have theoretically enabled 5G cell service on Mars, although some minor technological advancements will be necessary to make this happen. But their model does come with big error bars. Mars operates on a different schedule than Earth in more ways than one. A single Martian day lasts about 40 minutes longer than an Earth day, and a Martian year stretches across 687 Earth days compared with 365 days on Earth. Beyond those obvious differences, scientists needed to determine whether each second on Mars passes at the same rate as it does on Earth. An atomic clock placed on the surface of Mars would function normally. The clock itself would tick just as it does on Earth. The problem appears when that Mars clock is compared with one on Earth. Over time, the two clocks drift apart. The task for scientists was to determine exactly how large that offset becomes, similar to defining a planetary time zone. The calculation proved more complicated than expected. According to Einstein's theory of relativity, gravity alters the flow of time. Clocks slow down in stronger gravity and speed up where gravity is weaker. A planet's motion through space also affects how time passes, with orbital speed contributing additional changes.

The new model of Martian time is vastly more precise than the previous model. The previous model was created by the exact same people who made the new one. Nonetheless, it fits the data about a hundred times worse than the current best model of Moon to Earth time conversion. You’ll never guess who the authors are on that one. Fully synchronized interplanetary networks remain far in the future, as do permanent human settlements on Mars. Still, studying these timing challenges now helps scientists anticipate the obstacles ahead, Ashby noted. "It may be decades before the surface of Mars is covered by the tracks of wandering rovers, but it is useful now to study the issues involved in establishing navigation systems on other planets and moons," Ashby said. "Like current global navigation systems like GPS, these systems will depend on accurate clocks, and the effects on clock rates can be analyzed with the help of Einstein's general theory of relativity." Patla added that the research also advances fundamental science. Measuring how time behaves on distant worlds provides new tests of Einstein's theories of special and general relativity. "It's good to know for the first time what is happening on Mars time-wise. Nobody knew that before. It improves our knowledge of the theory itself, the theory of how clocks tick and relativity," he said. "The passage of time is fundamental to the theory of relativity: how you realize it, how you calculate it and what influences it. These may seem like simple concepts, but they can be quite complicated to calculate." When they compare their model of clock rate to real gravitational observations from Mars, their guesses are only off by an average of 100 ns (a billionth of a second) every day. This is astoundingly precise, but still a hundred times worse than their errors on the Moon, which are about 1 ns every day. Mars is a messier place to visit than the Moon, and time runs strangely there as the study concludes.